Python – Convert key-values list to flat dictionary

Last Updated : 21 Jan, 2025

We are given a list that contains tuples with the pairs of key and values we need to convert that list into a flat dictionary. For example a = [(“name”, “Ak”), (“age”, 25), (“city”, “NYC”)] is a list we need to convert it to dictionary so that output should be a flat dictionary {‘name’: ‘Ak’, ‘age’: 25, ‘city’: ‘NYC’}. For this we can use multiple method like dict, loop with various approach.

Using dict()

dict() constructor converts a list of key-value pairs into a dictionary by using each sublist’s first element as a key and the second element as a value. This results in a flat dictionary where the key-value pairs are mapped accordingly.

a = [("name", "Alice"), ("age", 25), ("city", "New York")]  # List of key-value pairs as tuples

# Convert the list of key-value pairs into a flat dictionary using the dict() constructor
res = dict(a)

print(res)

Output

{'name': 'Alice', 'age': 25, 'city': 'New York'}

Explanation:

List a contains tuples, where each tuple consists of a key and its corresponding value.
dict() constructor converts the list of key-value pairs into a flat dictionary, mapping each key to its value.

Using a Loop

For loop iterates through each tuple in the list a, extracting the key and value, and then adds them to a dictionary. The dictionary is built incrementally by mapping each key to its corresponding value.

a = [("name", "Alice"), ("age", 25), ("city", "New York")]

b = {}
for key, value in a:
    b[key] = value

print(b)

Output

{'name': 'Alice', 'age': 25, 'city': 'New York'}

Explanation:

for loop iterates through each tuple in the list a, unpacking it into key and value.
In each iteration, the key is used to assign the value to the dictionary b, effectively constructing the dictionary

Using Dictionary Comprehension

Dictionary comprehension {key: value for key, value in a} iterates through the list a, unpacking each tuple into key and value. It then directly creates a dictionary by assigning the key to its corresponding value

a = [("name", "Alice"), ("age", 25), ("city", "New York")]  # List of key-value pairs as tuples

# Use dictionary comprehension to create a dictionary by unpacking each tuple into key and value
res = {key: value for key, value in a}

print(res)

Output

{'name': 'Alice', 'age': 25, 'city': 'New York'}

Explanation:

Dictionary comprehension iterates over the list a, unpacking each tuple into key and value.
Each key is mapped to its corresponding value, and the comprehension directly constructs the dictionary res.

Using `zip()`

zip() function pairs the keys from a with corresponding values from b, creating key-value pairs. These pairs are then converted into a dictionary using dict().

a = ["name", "age", "city"]  # List of keys
b = ["Alice", 25, "New York"]  # List of values

# Use zip to pair each key from 'a' with the corresponding value from 'b', then convert the pairs to a dictionary
res = dict(zip(a, b))

print(res)

Output

{'name': 'Alice', 'age': 25, 'city': 'New York'}

Explanation:

zip() function combines elements from the lists a (keys) and b (values) into key-value pairs.
dict() constructor then converts the paired elements into a dictionary, mapping each key to its corresponding value.